In Indianapolis, an explosion occurs at a coffee house, resulting in the death of six people, and sixteen wounded. A man named Allen ARcher exits the coffee shop, having saved the life of a pregnant woman.
The BAU is called to investigate because this is the second bombing. The first one was at a school.
JJ and Kate interview Allen and his wife Sarah. Kate notices a kind of shrine set up to honor Sarah's first husband, a Navy Seal named Grant Ford.
Rossi and Morgan speak with the forensic specialist Dylan Einstein, who tells them the bomb was planted in the bathroom "Lethal Weapon style". Because of the bomb's placement, it would have been contained, except that it shot back and ruptured the natural gas line. Rossi and Morgan don't know if the murders were accidental or purposeful.
Later that night Allen leaves to go to the store. He gets in his truck, reads the news about the bombing on his tablet, notices the headline which says that the body count is now seven. He weeps for a moment, then notices that there's a bomb in his truck. When he had pressed on the pedal, he made the bomb active. He calls the BAU.
Morgan and Reid arrive and Morgan defuses the bomb, just as the bomb squad arrives. They put the family into protective custody.
While investigating Allen's background to see if he had knowledge of bombs, Garcia discovers that Brenda Archer's deceased husband's Navy Seal specialty was explosive ordinance.
While exploring Allen's truck, Morgan finds a bag filled with bomb-making instructional books. Allen and his wife are both brought in for further questioning.
Brenda tells Rossi and and JJ that after finding the bomb manuals, she had confronted her husband about them and that he told her to hide them. He told her he was studying the manuals because he wanted to understand what nearly killed him.
She tells Rossi that her husband has been working a lot of late nights - but Rossi replies that his workplace denies it.
As Kate and Hotch interview Allen, he finally admits to killing all of the people in the bomb blast.
The BAU realize that though they have Allen's confession for the coffee shop bomb, he didn't plant the bomb in his truck. His fear was too real. They determine there's a second bomber.
Kate and Hotch interrogate Allen again and realize he had nothing to do with the first bomb blast at the school. He had only planted the bomb at the coffee shop, and didn't intend to kill anyone. He had heard about the school bombing, and then decided to build a bomb of his own to impress his wife. He's a copy cat.
The media find out about the bomb on Allen's truck but don't yet realize he's the culprit in the coffee house bomb. They call for the mayor to give Allen the keys to the city. Hotch thinks that's a good idea because it will draw the original bomber out of hiding.
The unsub notices the news headline - that the mayor will give Allen the keys to the city. He has a bomb ready to go, and he sets it to 45 minutes.
A van rushes toward the award ceremony but is intercepted by the BAU and police. The driver says he was paid $200 and told to drive there. They open the van doors and find a decoy bomb.
The BAU know who the unsub is. JJ and Reid find him trying to plant a bomb in the basement where the ceremony is being held. JJ and Reid talk him out of arming it, then they take him into custody.